'House of the Dragon' star says she was 'quite comfortable' filming 'gnarly' incest scene

• Warning: Spoilers ahead for "House of the Dragon" season one, episode four, "King of the Narrow Sea."
• In the latest episode, Daemon Targaryen (Matt Smith) and his niece Rhaenyra have a steamy moment.

"House of the Dragon" star Milly Alcock said that she felt "quite comfortable" filming a steamy scene with Matt Smith, who plays her uncle.

In the latest episode of the "Game of Thrones" prequel, Daemon Targaryen (Smith) takes his niece Rhaenyra (Alcock) on a tour outside the royal castle at night. At one point, he brings her through a brothel, and the pair make out until Daemon pulls away and ditches her.

In an interview with the New York Post, Alcock, 22, said it wasn't awkward to film the scene with Smith, 39.

"No, strangely enough. [Matt Smith and I] were just kind of mates. So, it was quite comfortable," Alcock said. "We had an intimacy coordinator, and we worked with her through the rehearsal process and blocked it out months before."

She continued: "Clare Kilner, our director, made sure that we hadn't seen any of the brothel stuff until we were shooting. So, that was our first time walking through the brothel, and he's guiding her through the room with all of these other bodies. So, that was quite shocking. You're like, 'This is kind of weird and silly.' There were extras who we had just met who were like, 69-ing for 12 hours. It's pretty gnarly. We felt pretty overdressed because everyone else was nude."

Incestuous relationships have occurred several times in the "Game of Thrones" world, with one of the crucial plots of the first episode of the HBO hit series involving a secret relationship between Cersei Lannister (Lena Headey) and her twin brother Jaime (Nikolaj Coster-Waldau).

Alcock previously told the Post that Rhaenyra struggles to "tell the difference between platonic love, romantic love, and lust" due to her young age, which leads to the character's sexually-charged relationship with her uncle.

Rhaenyra has a similar relationship with her guard, Ser Criston Cole (Fabien Frankel), to whom she ends up losing her virginity in episode four, and her former friend turned stepmother, Alicent (Emily Carey).

Carey previously told Insider during a roundtable interview that Rhaenyra and Alicent are "a little bit in love."

"I think any woman could think back to the best friend that they had at 14 years old, and it's a relationship and a closeness unlike any other," Carey said. "You do toe the line between platonic and romantic."

New episodes of "House of the Dragon" air Sundays on HBO at 9 p.m. ET.